42991 ÷ 3 = 14330 R1
Alright, let's work through the division of 42991 by 3 step by step.

Step 1:
3 goes into 4 1 times with a remainder of 1.
Write down 1 as next digit of of the result. 
Result so far: 1
Subtract 3 from 4 to get 1.
Bring next digit (2) of the dividend behind the 1 and repeat the process: 12 / 3

Step 2:
3 goes into 12 4 times with a remainder of 0.
Write down 4 as next digit of of the result. 
Result so far: 14
Subtract 12 from 12 to get 0.
Bring next digit (9) of the dividend behind the 0 and repeat the process: 9 / 3

Step 3:
3 goes into 9 3 times with a remainder of 0.
Write down 3 as next digit of of the result. 
Result so far: 143
Subtract 9 from 9 to get 0.
Bring next digit (9) of the dividend behind the 0 and repeat the process: 9 / 3

Step 4:
3 goes into 9 3 times with a remainder of 0.
Write down 3 as next digit of of the result. 
Result so far: 1433
Subtract 9 from 9 to get 0.
Bring next digit (1) of the dividend behind the 0 and repeat the process: 1 / 3

Step 5:
3 goes into 1 0 times with a remainder of 1.
Write down 0 as next digit of of the result. 
Result so far: 14330
Subtract 0 from 1 to get 1.

The final result is 14330 with a remainder of 1.